Carbapenemase Producing Gram Negative Bacilli Causing Urinary Tract Infections, in National Hospital, Colombo, Sri Lanka.

Abstract

Background: Urinary tract infections (UTIs) are a major problem all around the world. Most of the UTIs are caused by Gram-negative bacilli (GNB). Carbapenem drugs are the last line of defense against UTIs caused by GNB. Determining the prevalence of carbapenem resistance GNB-causing UTIs is essential, as they have become resistant to a range of antibiotics. Objectives: To evaluate the presence of carbapenemase-producing GNB (CP-GNB) and to identify the antibiotic susceptibility patterns of GNB-causing UTIs at the National Hospital, Colombo, Sri Lanka Methods: This study included 142 GNB isolates (urine). Gram staining was performed to identify GNB isolates taken from Cystine Lactose Electrolyte deficient medium. Oxidase test was done to differentiate Pseudomonas aeruginosa from Enterobacteriaceae. Antibiotic susceptibility patterns were identified by the Disc diffusion method. Carbapenemase production was determined by carbapenem inactivation method (mCIM). The data were analyzed using SPSS version 29.0.2.0. Chi-square method and descriptive statistics were used. Results: Out of 142 GNB isolates, the commonest were Enterobacteriaceae, 125 (88.03%). The other 17 (11.97 %) isolates were P. aeruginosa. Among total GNB isolates, 27.46% were positive for mCIM test, and 64.09% were negative for mCIM. Out of total Enterobacteriaceae, 30 (24.0%) were mCIM positive, 10 (8.0%) were mCIM intermediate, 85 (68.0%) were mCIM negative. Out of total P. aeruginosa, 9 (52.94%) were mCIM positive, 2 (11.76%) were mCIM intermediate and 6 (35.30%) were mCIM negative. They also showed significant resistance to cefuroxime (30 µg), cefpodoxime (10 µg), Amoxicillin-clavulanic acid (30 µg), and ciprofloxacin (5 µg) (p<0.001). The mCIM-negative isolates showed significant resistance towards nalidixic acid (30 µg), and ciprofloxacin (5 µg) (p<0.001). Conclusion: CP-GNB showed significant resistance to several routinely used antibiotics